Another update. I've confirmed there is a definite slow down in the marking menu since this update. I reset Alias as you suggested, even doing it manually (not importing/loading any preferences), and did the same on an earlier version of Alias so that I could compare workflows.
I tested using the same commands of creating lines, projecting, trimming, untrimming, deleting repeating several times to get the flow within both. All of these for me are within my marking menu.
In the earlier version of Alias, I can do all of the above without missing a beat. And when I'm using the older version of Alias, I can once again increase my speed. Then when I jump back into the newer update of Alias, it hangs up and doesn't register my selections in time, causing errors. Even if I do slow myself down to reduce errors, it causes tension in me to slow down my flow, and muscle aches faster than normal because I'm holding the movements longer.
I can't measure it, but there's no doubt it is slower, and as far as I can tell, it's something to do with this update, and nothing to do with my preferences being corrupt. Even if it is only 1/100th of a second slower, I retract my earlier comment that this is not really an "issue". After comparing it to the old version, I think this is a major issue. It may seem minimal, and it may not even affect most users, but it definitely can affect performance timing and stress levels while working.